.relative(@left:0px,@top:0px) {
  position: relative;
  left: @left;
  top: @top;
}
.absolute(@left:0px,@top:0px) {
  position: absolute;
  left: @left;
  top: @top;
}
.toBlock(@width:0px,@height:0px) {
  display: block;
  width: @width;
  height: @height;
}
.center(@top:0) {
  margin: @top auto;
}
